Extensive efforts have been devoted to explore transport behaviors through various molecules and clusters, which are promising building blocks in molecular electronics. Here, we examine the spin-polarized electronic structures and transport properties of a three-shell icosahedral matryoshka cluster, Pb@Mn12@Pb20, by performing density functional theory calculations combining with non-equilibrium Green's function method. Theoretical results clearly reveal that, twelve Mn atoms in the middle layer anti-ferromagnetically couple with the center Pb atom and Pb atoms in the outlayer, while the Pb@Mn12@Pb20 cluster still has a huge magnetic moment of 28.0 bohr magneton, mainly contributed by these Mn atoms. The calculated spin-resolved transmission spectra of the proposed Pb@Mn12@Pb20 junctions exhibit robust spin filtering effect, which is not sensitive to the anchoring distance and the adopted electrode materials, and the conductance through the cluster under the small bias voltage is mainly determined by the spin-up electrons. These findings indicate that this kind of three-shell matryoshka cluster with huge magnetic moment holds potential applications in molecular spintronic devices.

Codoping can effectively engineer the band structures of photocatalysts (e.g. TiO2) to enhance their photoelectrochemical performance, however, previous investigations mainly focused on codoped bulk materials. In this work, we explore the (Rh + F) surface codoping effect on anatase TiO2 (101) and (001) facets for solar water splitting by performing extensive density functional theory calculations. According to the calculated defect formation energies, we find that the noble metal (Rh) atoms can be stably doped at the anatase TiO2 (101) surface with the aid of the codoped F atoms, thus can act as active sites for photocatalytic H2 evolution, which also provides the possibility of single-atom Rh catalysis on the (Rh + F) codoped anatase TiO2 (101) surface. The band gap of the codoped system is narrowed to about 2.14 eV through introducing several occupied and delocalized intermediate states which prevent the recombination of photogenerated carriers. Remarkably, the valence band maximum and conduction band minimum of the (Rh + F) codoped anatase TiO2 (101) surface match well with the water redox potentials and the visible light absorption is significantly enhanced. These findings imply that this kind of surface codoping is an effective approach to obtain visible light photocatalysts for water splitting.

Carbon-doped boron nitride nanostructures including nanosheets, nanoribbons, and nanotubes have drawn enormous research attention because of their tunable electronic properties and widespread applications. In this work, we explore the electronic and magnetic properties of graphene flake-doped single-walled boron nitride nanotubes (BNNTs) on the basis of first-principles calculations. Theoretical results reveal that the band structures of these doped BNNTs can be effectively engineered by embedding graphene flakes with different sizes and shapes. Moreover, the Lieb theorem works for the triangle graphene flake-doped BNNTs, and the corresponding doped systems are ferromagnetic, originating from the spin-polarized interface states. All BNNTs embedded with the triangular graphene flakes with relatively small sizes are typical bipolar magnetic semiconductors, which can be easily tuned into half-metals by carrier doping, opening the door to their promising applications in spintronic devices.